Earth’s
ionosphere responds quickly to the enhanced X-rays andultraviolet
(UV) radiation emitted from the Sun during solar flares. Ground and satellite
based observations are important for unravelling the consequencesof
these essentially unpredictable events. Regular ionospheric soundings are made
over Ahmedabad (23oN, 72.4oE) using KEL digital
Ionosonde. Using this data, the influence of the excess X-ray emission from the
flares / CMEs in different regions of the Earth’s ionosphere over Ahmedabad has
been studied. Based on the X-ray spectral characteristics of the flares, the
variation in the minimum frequency of reflection, fmin, an indicator
of the ionization in D-region of ionosphere, in contrast to daily quiet time
variation, has been measured. The studies of the excess absorption, due to the
solar flares, in the D-region of ionosphere over Ahmedabad are made for the
events during 1996-2000. The deviation from Chapman’s layer behaviour of
E-layer over Ahmedabad during few solar flares have been also found.